It is common for a motor be used to drive a shaft, which transfers torque from the motor to be used as mechanical energy for driving a pump, ship propeller or any number of other applications. In some cases, the torque must be carried over long distances that exceed the length of a single shaft attached to the motor and one or more additional shafts are required to connect the motor to the ultimate device to which the mechanical energy is being transferred. In cases where torque is to be transmitted from one shaft to another, any of several coupling types have heretofore been used; however, each presents problems.
Among the simplest solutions is the use of two threaded shafts joined by a threaded coupling. While effective in situations in which the shafts turn only in one direction, this solution does not adequately work in environments where the shafts are intended, or can, rotate in an opposite direction. In fact, this common solution can have significant adverse consequences by causing the two shafts to fly apart from one another if, for example, the polarity of a motor driving the shafts is inadvertently switched during a repair operation, particularly when the shafts are positioned vertically for use in a down-well application. Furthermore, the need for threaded shafts having precise machining results in increased material costs.
Another common solution is through the use of a fastener or other device attached to a first shaft that engages and draws together a corresponding socket or other device attached to the second shaft. However, a significant drawback in these type of devices is that they require relative movement of the two shafts with respect to one another as they are being drawn toward each other as part of the coupling process. Thus, this type of coupling cannot be used in precision applications where one or both of the shafts to be connected are already in place or otherwise cannot be moved.
Another current solution is the use of two clamps which are fastened together, either directly, or through the use of a spacer to which each of the clamps are coupled. This results in increased material cost by requiring the presence of at least two clamps, plus that of any spacer. It also results in increased difficulty during maintenance operations as the clamps must first be decoupled from one another before the shafts can be removed from the clamp. Further, the need to fasten the two clamps together can also result in an increased diameter of the coupling to accommodate the fasteners. This can reduce the types of applications in which the coupling can be used, particularly in down-well applications where space is at a premium and may be limited by the diameter of the well casing in which it is employed.
Still another type of solution is the use of hydraulic clamps. While hydraulic clamps are useful in some situations, the principles of their operation require the presence of a hydraulic fluid that creates additional complexities in the operation and, importantly, the maintenance of such clamps.
These and other drawbacks are found in known devices for coupling two shafts for the transfer of torque.
What is needed is a connection assembly that can provide a single device to connect two shafts that can be easily assembled and maintained, while providing for the transfer of torque regardless of the direction of rotation.